1. Field of the Invention
The present invention pertains to a cooling apparatus, and more particularly, but not by way of limitation, to a cooling apparatus using stacked low profile extrusions (LPE""s).
2. History of Related Art
As is explained in greater detail hereinbelow, LPE cooling devices are extremely useful in printed circuit board (PCB) level cooling of electronic components, and for use as heat exchangers in applications where space is limited and/or low weight is critical.
LPE refers to a heat exchange apparatus comprising an integral piece of metal having a series of micro extruded hollow tubes formed therein for containing a fluid. LPE""s preferably have multi-void micro extruded tubes designed to operate under the pressures and temperatures required by modern environmentally safe refrigeration gases and to resist corrosion. Aspects of the LPE application to the present invention are set forth and shown in co-pending U.S. patent application Ser. No. 09/328,183 assigned to the assignee of the present invention and incorporated herein by reference.
Low profile extrusions can currently be manufactured with a profile, or height, as low as about 0.05 inches and with tubes of varying inner diameters. Of course, future advances may allow such low profile extrusions to be manufactured with an even smaller profile. Such low profile extrusions have been conventionally used in heat exchanger applications in the automotive industry, and are commercially available in strip form (having a generally rectangular geometry) or coil form (a continuous strip coiled for efficient transport).
An example low profile extrusions is described in a brochure entitled xe2x80x9cThermalex, Inc.xe2x80x94Setting A Higher Standard in Aluminum Extrusionsxe2x80x9d (hereinafter the xe2x80x9cThermalex Brochurexe2x80x9d) provides additional detail regarding the Thermalex low profile extrusions and is incorporated herein by reference.
U.S. Pat. No. 5,342,189 to Inamura, et al, which is incorporated herein by reference, provides additional detail regarding an extrusion die for making such low profile extrusions. The extrusion die is used for making multi-cavity flat aluminum tubes, which are used for small heat exchanger components, in automotive air-conditioners, condensers, and radiators. The insert die is composed of a male die section having a protrusion part and a female die section, having a die cavity, and is held detachably in a die holder. The male section is a roughly rectangular plate-shaped component, and has an integrally formed twist prevention region which is inserted into the receiver groove of the female section which is integrally formed thereon. The protrusion part defines the cavity shape of the multi-cavity flat tube, and the female section has the die cavity of the required cross sectional shape to define the outer shape of the tube.
U.S. Pat. No. 5,353,639 to Brookins, et al, which is incorporated herein by reference, provides additional detail regarding a method and apparatus for sizing a plurality of micro extruded tubes used in such low profile extrusions. As described by the Brookins patent, a predetermined number of micro extruded tubes are stacked on the base fence between the fixed side fence and the clamping fence. The internal webs of the tubes are aligned throughout the stack, perpendicular to the plane of the base fence. The clamping fence is moved toward the stack of tubes to prevent the stack from moving laterally. The die platen is moved toward the stack of tubes and the mating surface of the die platen is in mating engagement with a side surface of the uppermost tube in the stack. A predetermined amount of pressure is applied to the stack of tubes through the die platen. The pressure is applied equally across the entire side surface of the uppermost tube and is transmitted equally through all the tubes of the stack in the sizing die.
Other developments in cooling apparatus may be seen in U.S. Pat. No. 5,285,347 to Fox et al., which describes a hybrid cooling system for electrical components. A hybrid heat sink is specially adapted to transfer heat to two cooling fluids. This heat sink is incorporated into a cooling system in which some of the electronic components of an electronic device may be cooled by two cooling fluids and some electronic components may be cooled by one cooling fluid. The electronic components are mounted on a circuit board. In the Fox reference, one of the cooling fluids is air and one is a liquid. The hybrid heat sink is attached to electronic components that cannot be cooled to the normal operating range by the cooling air alone. The cooling air is caused to flow over the surface of the heat sink, removing some of the heat. In addition, the cooling liquid is caused to flow through the heat sink, thereby removing additional heat.
In addition, U.S. Pat. No. 5,901,037 to Hamilton, et al. describes a system for closed loop liquid cooling for semiconductor RF amplifier modules. The system comprises a combination of a plurality of elongated microchannels connected between a pair of coolant manifolds for conducting liquid coolant beneath the transistors to dissipate the heat generated thereby. The system also includes a heat exchanger, a miniature circulating pump located on the module, and passive check valves having tapered passages for controlling the flow of coolant in the loop. The valve comprises a truncated pyramid-shaped microchannel valve having no moving parts and is fabricated so as to be a part of either the circulating pump assembly, the coolant manifold, or the microchannels.
The present invetnion relates to a low profile extrusion cooling method and apparatus. More particularly, the present invention relates to a stacked low profile phase plane heat pipe cooling system and method. In one aspect, the invention includes stacked, low profile phase plane heat pipes, wherein heat transfer fluids contained therein are induced to flow by heat absorbed thereby. The stacked, low profile cooling system of the present invention includes a first low profile extrusion. Stacked on top of the first phase plane heat pipe is a second low profile phase plane heat pipe also in thermal contact with the first phase plane heat pipe. A third low profile phase plane heat pipe may be stacked on top of the first and second low profile phase plane heat pipes. The third low profile phase plane heat pipe is in thermal contact with a top surface of the first low profile phase plane heat pipe.
In another embodiment, a first, second and an optional third thermally conductive spacer block are provided on the undersurface of each low profile phase plane heat pipe and are in thermal contact therewith. The first, second, and optional third thermally conductive spacer blocks provide a conduit for heat transfer from the heat source up to and through the stacked, low profile cooling system.
In yet another embodiment, cooling fins are provided on the undersurface and topsurface of the low profile phase plane heat pipes. The cooling fins include elongated arrays in thermal contact with the phase plane heat pipes.
In still another embodiment, the low profile phase plane heat pipes are low profile phase plane heat pipes (heat pipes). The low profile phase plane heat pipes are preferably positioned at an angle between 0 and 90 degrees extending laterally from an element which may be either a heat source or the thermally conductive spacer block. The angle further facilitates the movement of evaporated fluid into the extremities of the heat pipes for the condensation thereof and the flow of fluid back into evaporator sections where additional heat may be absorbed.
The present invention pertains to an improved, high volume, stacked LPE apparatus and method for manufacturing thereof.